JPH0547661A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method for obtaining a polysilicon thin film having large crystal grain size. CONSTITUTION:Polysilicon nuclei 4 are formed by an optical CVD method, an amorphous silicon film 2 is then formed by a CVD method, and a polysilicon thin film 5 having large crystal grain size is formed by low temperature annealing at 650 deg.C or lower. The polysilicon thin film having the large crystal grain size is obtained, and when it is used as an electrode of a TFT transistor, an OFF current of the transistor can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device for forming a silicon thin film having a large crystal grain size.

[0002]

2. Description of the Related Art FIG. 2 is a sectional flow chart for explaining a conventional method for forming a silicon thin film, wherein 1 is a substrate, 2 is an amorphous silicon film, and 5 is a polysilicon film.

A conventional method for forming a silicon thin film will be described below with reference to this drawing. An amorphous silicon film 2 is formed on the substrate 1 by the CVD method (FIG. 2 (a)), and the amorphous silicon film 2 is annealed at about 600 ° C. to form a polysilicon film 5 (FIG. 2 (b)). ).

[0004]

In the conventional semiconductor device, the polysilicon film is formed by annealing the amorphous silicon film as described above, but there is a problem that the crystal grain size of polysilicon does not become so large. It was

The present invention has been made to solve the above problems, and an object thereof is to obtain a method of manufacturing a semiconductor device capable of obtaining a polysilicon thin film having a larger crystal grain size.

[0006]

According to a method of manufacturing a semiconductor device according to the present invention, a polysilicon nucleus is formed by a photo CVD method, an amorphous silicon film is further formed by the CVD method, and a crystal is formed by low temperature annealing at 650 ° C. or lower. A polysilicon thin film having a large grain size is formed.

[0007]

According to the method of manufacturing the semiconductor device of the present invention,
Polysilicon nuclei are formed by the photo-CVD method, an amorphous silicon film is formed by the CVD method, and then low-temperature annealing at 650 ° C. or less is performed to form a polysilicon thin film having a large crystal grain size. When used as a transistor, off current can be reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional flow chart showing a method for forming a silicon thin film according to an embodiment of the present invention, in which 1 is a substrate, 4 is a polysilicon nucleus, 2 is an amorphous silicon film, and 5 is a polysilicon film.

A method of forming a silicon thin film will be described below with reference to this drawing. A polysilicon nucleus 4 is formed on the substrate 1 by the photo CVD method (FIG. 1 (a)), and then an amorphous silicon film 2 is formed by the CVD method (FIG. 1 (b)).
By annealing at a low temperature of 0 ° C. or lower, crystals are grown with the polysilicon nuclei 4 as nuclei to form a polysilicon thin film 5 having a large crystal grain size (FIG. 1 (c)).

In this embodiment as described above, the crystal grows with the polysilicon nuclei as nuclei, so that a polysilicon thin film having a large crystal grain size can be easily formed. Therefore, a semiconductor device suitable for use as a TFT transistor can be obtained.

[0011]

As described above, according to the present invention, the polysilicon nuclei under the amorphous polysilicon are 650
Since the growth is performed by low temperature annealing at a temperature of ℃ or less, it is possible to form a polysilicon thin film having a large crystal grain size, and it is possible to reduce the off current when used as a TFT transistor, for example.

[Brief description of drawings]

FIG. 1 is a sectional flow chart showing a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a sectional flow chart showing a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 1 substrate 2 amorphous silicon film 3 mask 4 polysilicon nucleus 5 polysilicon film

Claims (1)

[Claims] 1. A step of forming a polysilicon nucleus by a photochemical vapor deposition method (hereinafter referred to as a photo-CVD method), a step of forming an amorphous silicon film by a CVD method, and a low temperature anneal at 650 ° C. or lower. And a step of forming a polysilicon film having a large crystal grain size.